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7/27/2019 Basic-well-logging-Design (Sigit Sutiyono, Unocal)
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BasicWellLoggingDesignBasicWellLoggingDesign
CoordinatedByCoordinatedBy
SigitSutiyonoSigitSutiyono
UnocalIndonesiaCompanyUnocalIndonesiaCompany
A One-day Course on
Consortium Alumni Association Presents
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gendgend Introduction
(8:15)
LectureI BasicTheory/Interpretation
Break(10 10:15)
LectureII LoggingProgram/Design
Break(12:00)
Workshop
(1:30
4:00) Wrapup(4:00 5:00)
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ObjectivesObjectives
Get
to
know
various
log
measurements Recognizefluidtypeandlithologyofmajorreservoirs,
andsomepracticalapplicationoflogdata
Familiarizewithfactorsaffectingthelogresponse
Understandthestrategyinwellevaluation
Gettoknowvariousapproachestowellloggingdesign
Exercisewithwelllogdesign
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According to
4th Edition of J.A.Jacksons Glossary of Geology:
Log : A continuous record as a function of depth,
usually graphic and plotted to scale on a narrow
paper strip, of observations made on the rocks
and fluids of the geologic section exposed inthe well-bore.
DefinitionDefinition
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Wireline Logging Logging while Drilling
Cable
Tools
LWD Tools
Mud inMud out
Drill Bit
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WellLogging
HistoryWell
Logging
History
Thefirstelectricallogwasintroducedin1927inFranceusingstationed
resistivitymethod.
Thefirst
commercial
electrical
resistivity
tool
in
1929
was
used
in
Venezuela,USAandIndonesia.
SPwasrunalongwithresistivityfirsttimein1931
Schlumbergerdevelopedthefirstcontinuousrecordingin1931
GRandNeutronlogswasstartedin1941
Microresistivityarraydipmeterandlateralogwerefirsttimeintroduced
in1950s
Thefirstinductiontoolwasusedin1956followedbyFormationtester
in1957,
Fomation
Density
in
1960s,
Electromagnetic
tool
in
1978
and
mostofImaginglogsweredevelopedin1980s
Advancedformationtesterwascommercializedinearly1990s
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The First Log recorded in 1927
Well in Pechelbronn - France Surface Recording Instrument
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LogMeasurementsLogMeasurements
Logisanindirectmeasurementofformationproperties
exposedbythewellboreacquiredbyloweringadeviceor
acombinationofdevicesinthewellbore.
Practical definition of a log
A Formation Evaluation Specialist is essential to understand
The theory of measurements, quality control, interpretationprinciples, geophysics and petroleum geology as well as
petroleum reservoirs
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Advantagesand
Limitations
of
Well
LoggingAdvantages
and
Limitations
of
Well
Logging
Advantages:
- Continuous measurements
- Easy and quick to work with
- Short time acquisition
- Better resolution than seismic data
- Economical
Limitations:
- Indirect measurements
- Limited by tool specification
- Affected by environment
- Varying resolution
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BasicTheoryofMeasurementsBasicTheoryofMeasurements
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Logsare
Implied
MeasurementsLogs
are
Implied
Measurements
Logisnotadirectmeasurementofformationproperties,itisanimplied
measurementbasedononeorcombinationofthefollowingdevices
Electrical (Resistivity and
Induction)
Acoustic
Nuclear
Electromagnetic
Magnetic
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BasicTheory
on
ResistivityBasic
Theory
on
Resistivity
Current path
Unit volume filled with only water
Current path
Unit volume with water and matrix
Rw
Ro
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Typical Formation
Rt
Water
Sand grain
Grain surface water
Oil
Measured by the tool
Current path
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Resistivityand
Measurement
ConceptResistivity
and
Measurement
Concept
Resistivity is the ability of a substance to impade the flow of electrical current
Rw - Formation Water resistivityE - Voltage difference across the formation
A - Cross sectional Area
L - Length of brine containerr
I - Current
Rw =
E * A
I * L
L
I E
ARw
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Resistivityand
Measurement
ConceptResistivity
and
Measurement
Concept
Schematic diagram of how an induction tool works
Primary magnetic field
created by transmitter
Magnetic field induces
a current in the ground loop
Secondary magnetic field
Created by the ground loop
Secondary magnetic field
Induces a current to flow in the receiver
Transmitter
Receiver
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Resistivity is the key to hydrocarbon saturation determinationResistivity
ApplicationResistivityApplication
Water Saturation EstimationArchies Equation
Sw =F * Rw
Rt
SW - Water saturation
Rw - Formation water resistivityRt - True Formation resistivity
( )1/n
where F =1.0
Porm
Sh = 1 - Sw
Resistivity is also used for well to well correlation, and to pick fluid contacts
F - Formation factor
n - Saturation exponentm - Cementation factor
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SpontaneousPotential
Log
(SP)Spontaneous
Potential
Log
(SP)
SPmeasurementisbasedonElectricalcurrentsflowinginthe
mudfrom
electrochemical
and
electrokinetic
Salinitydifferencebetweenmudflitrateandformationwaters,
ionsmovementcreatescurrentsmeasuredinmVolt
NegativeorPositiveSPcurvedeflectionrepresentswhichfluid,
formationor
mud
filtrate,
has
more
ionic
charge.
Itonlyworksinwaterbasedmud!
The
use
of
SP
log;
bed
boundary,
distinguishing
permeable
from
impermeablerock,shalynessindicator, Rwdeterminationand
wellcorrelation.
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SpontaneousPotential(SP)SpontaneousPotential(SP)
SP
Shale
Sand Thick clean wet sand
(-) (+)
- - - - - - -
- - - - - - -
Thick shaly wet sand
Thick clean Gas sand
Thick shaly Gas sand
Rmf >> Rw in all sands
Hydrocarbon effect
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SpontaneousPotential
(SP)Spontaneous
Potential
(SP)
20
40 mV
7470
7430
Given:
Rmf = 0.51 at 135 F
Rm = 0.91 at 135 FTD = 8007 ft
Bottom hole temp.= 135 F
Surface temp. = 60 F
Determine Rw ?
SP
Limitation
SP is not reliable when you have no or very small contrast
Between Formation water salinity and mud filtrate salinity resulting in no
to small SP deflection
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Rwcalculation
from
SP
logRw
calculation
from
SP
log
SSP = -K log
Rmfe
Rwe
Steps of Calculation;
- Determine Temperature at Depth of interval
- Correct Rm and Rmf to this temperature (gen-9)
- Determine SP (log) from shale baseline
- Correct SP to SSP using SP thickness corr. chart
- Determine Rmf/Rwe ratio using SP-1 chart- Determine Rwe from above equation or SP-1 chart
- Correct Rwe to Rw using SP-2 chart
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GammaRay
Log
(GR)Gamma
Ray
Log
(GR)
GRtoolmeasuresnaturalradioactivityoftheformationfrom
the
emmision
of
all
these;
(Total
GR)Potasium,UraniumandThorium
GRlogisusedfor;WelltowellgeologicalcorrelationBeddefinition,moreaccuratethanSPlog
Shale
Volume
Indicator
(most
reliable)
Lithologyandmineralogyindicator(NGT)
IGR =GRlog - GRmin
GRsh - GRmin
IGR - Gamma ray index
GRmin - GR clean
GRsh - GR shale baseline
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GammaRay
Log
(GR)Gamma
Ray
Log
(GR)
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GammaRay
Log
(GR)Gamma
Ray
Log
(GR)
Mineral Density DT GR
Quartz 2.64 56 0-15Calcite 2.71 49 0-15
Dolomite 2.85 44 0-15
Orthoclase 2.52 69 220
Micas 2.82 49 275Kaolinite 2.41 - 80-130
Chlorite 2.76 - 180-250
Illite 2.52 - 250-300
Montmorillonite 2.12 - 150-200Anhydrite 2.98 50 low
Pyrite 4.99 39 low
Coal 1.47 high low
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Gamma
Ray
Log
(GR)Gamma
Ray
Log
(GR)
Well-1 Well-2Well-7
GR Res
GR Res
GR Res
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Natural
Gamma
Ray
Log
(NGT)Natural
Gamma
Ray
Log
(NGT)
NGT tool measures the spectrum of
Potasium,Uranium, and Thorium
NGT log is used for;
- Study of Depositional Environments
- Geochemical logging
- Shale typing
- Source Rocks
- Diagenetic History
- Vclay content correction
With combination of Photoelectric curve can be
used for clay and mica type identification
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NaturalGamma
Ray
Log
(NGT)Natural
Gamma
Ray
Log
(NGT)
0 2 4 6 8 10
2
4
6
8
10
0
K, Potasium (%)
Pe
Kaolinite
Montmorillonite
Illite
Glauconite
Muscovite
Biotite
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Density
LogDensity
Log
Densitytoolisoneofthemostimportantinstrumentsusedto
evaluate
formations
which
measures
formation
density
and
directlytiestoformationporosity
Thedensitytoolmeasurestheelectrondensity,byemittinggammarayfromradioactivesourceandreturningtotwodetectors
TheamountofGammaraysthatreturndependonthenumberofelectronspresent, electrondensityisrelatedtobulkdensityofmineralorrock
InmostcasesenvironmentalcorrectionforDensitylogisnot
significant,field
log
density
can
be
readily
used
for
interpretation
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Density
LogDensity
Log
Main categories in the process of GR energy loss due to
collisions with other atomic particles:
Compton Scattering is selected to be the energy level to
generate GR of the Cesium 137 radioactive source at 662 keV
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Density
LogDensity
Log
Porositydeterminationfromdensitylog:
POR =RHOBma - RHOBlog
RHOBma - RHOBfluid
RHOBma - Matrix density
RHOBfluid - Formation fluid density
RHOBlog - Log density
PORd - Density derived porosity
Exercise: Determine porosity of limestone with field log
density inicated 2.5 gr/cc.
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NeutronLogNeutronLog
ThetoolmeasurestheHydrogenIndexwhichisthequantityof
Hydrogenperunitvolume
Thetools
emit
high
energy
neutrons
either
from
radioactive
sourceorminitron.Theyaresloweddownbycollisionswith
formationnuclei,collisionwillresultenergyloss,andthe
elementmostlysloweddownisH
Waterhas
high
neutron
counts,
Oil
has
alittle
less
counts
than
Water,Gaswillhaveverylowneutroncounts
Neutronlogisverysensitivetoenvironmentchange;borehole
size,mudcake,mudweight,temperature,standoff,pressure
andformationsalinity,measurementiscompensationoffar
andnearcountrates.
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Neutron
LogNeutron
Log
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Neutron
LogNeutron
Log Neutrontoolhasawiderangeofapplications
PorosityDetermination
Gas
DetectionBoreholeandformationsalinity
ReservoirSaturation
ReservoirMonitoring
BoreholeFluiddynamics
NeutronradioactivesourceinnormallyusesAm241
Exercise Neutron Log environmental correction
Given: Uncorrected neutron porosity of 34%, 14 borehole size,
0.25 mud cake, 200 kppm borehole salinity, 12 ppg mud at
170 F, 5000 psi pressure, using water based mud with formation
salinity of 50 kppm.
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Acoustic
LogAcoustic
Log Sonictoolgeneratesacousticsignalstomeasurethetimetravelto
passthroughaformation,logmeasurementintimerequiredto
travel
in
one
foot
formation
(microsec/foot) Rockpropertiescanbeimpliedfromsonicmeasurements;
Porosity, Lithology, Gasshows,CompactionandRockstrength
Maincurrentuse: SeismicTie
Mechanical
properties
Fractureidentification
Tooltypes; Boreholecompensatedsonic
Longspacingsonic
Arraysonic
tool
Ultrasonicboreholeimage
Dipoleshearsonicimage
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Acoustic
LogAcoustic
Log
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Acoustic
LogAcoustic
Log
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Special
ToolsSpecial
Tools
Resistivity Based Imaging Tool
- Pad device on 4 to 6 arm caliper, few mm resolution
- Application: Thin bed Evaluation, Dip meter,Paleostream direction, fracture evaluation, stratigraphy.
Nuclear Magnetic Resonance
- Using Permanent magnet to realign hydrogen protons to new
magnetic field, a Lithology dependance porosity, saturartionand permeability estimation
Dipole Shear Sonic
- Shear measurement, AVO and Rock mechanics applications
Borehole sonic imaging- Acustic based bore hole imaging for 360 deg coverage, lower
resolution than resistivity based imaging tools.
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Special
ToolsSpecial
Tools continued
Modular Formation Test
- Very robust formation tester with the capability to take
unlimited pressure tests, pump the fluid into the borehole,identify the fluid type before sampling
Wellbore Seismic
- VSP: Vertical seismic profile surface guns, wellbore detectors
- SAT: Seismic acquisition tool- WST: Well seismic tool
- DSA: Downhole seismic array tool (3 axis geophones)
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WellboreSeismicWellboreSeismic
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Log
and
Seismic
Tie
EffortLog
and
Seismic
Tie
Effort
LogDataValidation
Check
the
log
qualitySeeifthereisanymissinglogdata
Determinewhethersonicpeaks/anomaliesrepresentingformation
Logediting
Velocity
Correction
Sonic
over
VSP
(using
4
2
msec
resolution)
SyntheticSeismicGeneration
AcousticImpedance
ConvolutionWavelettotieseismicandlogpeaks
*ExtractedWavelettoutilizewaveletasseenintheseismic
itis
highly
recommended
(similar
apperance)
*RickrWaveletcommonlyusedtohavezerophase
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Synthetic
SeismogramsSynthetic
Seismograms
SyntheticSeismogramsareusedtocorrelateseismicsections
Theoreticallythis
method
uses
many
simplification
and
assumptions
put
intothemodel
Itprovidesimportantlinktounderstandthetiebetweenseismicdataand
welllogresponses
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VSP&VSP&
SeismicSectionSeismicSection
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Velocity
SurveyVelocity
Survey Velocityorcheckshotsurveysareperformedinthewellboretoobtain
verticaltravelpathsthroughtheformationsbylocatingsourcesand
detectors/receiversat
certain
configuration,
normally
the
receivers
are
placednearthegelogicalhorizons
Thesurveyonlyutilizefirstarrivaltouseintherecordedseismictrace
Firstarrivalsarethenconvertedintoverticaltraveltimesontimedepth
graphswhich
can
be
used
to
calculate
average
velocities
Soniclogcalibrationneedstobedonepriortogenerationofsynthetic
logs,normallyboreholeeffectsarefoundveryoftencausingdrift whichistoberemovedtopreventshiftingintimeofseismicreflectionsor
pesudoevents
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Vertical
Seismic
ProfileVertical
Seismic
Profile VerticalSeismicProfiling(VSP)usesbothentirerecordedseismictraceand
firstbreak. Receiversarespacedatveryclosed intervalsinthewellborein
order
to
get
a
seismic
section
in
the
wellbore Theseismicwaveandalleffectsaremeasuredasafunctionofdepthasit
propagatesthroughtheformations
Thrreceiversareclosetoreflectorswhereupgoinganddowngoingwaves
arerecordedasafunctionofdepth
Thedown
going
wavelets
are
used
to
design
deconvolution
filters
IngeneralVSPprovidemuchbetterspatialandtemporalresolution,the
signalchangesintermofbandwidthandenergylossaremeasured
ApplicatiosofVSParetocorrelatetheactualseismiceventswithmore
confidence,
and
with
much
better
resolution
due
to
shorter
travel
paths
it
canprovideatooltogeneratehighresolutionmaps,andbetterestimateof
rockproperties
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Basic
Concept
of
VSPBasic
Concept
of
VSP
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BasicConceptofVSPBasicConceptofVSP
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Offset
VSPOffset
VSP
OffsetVSPareusedtodetectfaultsandpincouts
developedtoilluminatestructureawayfromthewellbore
Multiple offset and walkaway VSP
Multiple offset VSP were developed to provide high-resolution seismic
structural details in the area where interference from the shallow layers
The disadvantages is very time consuming, it requires few days for the
acquisition by putting multiple source positioned in different locations
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OffsetVSPOffsetVSP
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BasicLog
InterpretationBasic
Log
Interpretation
Logs Data Applications
Determine depth and thickness
Identify productive zones Distinguish fluid types, gas, oil and water
Estimate hydrocarbon reserve
Help geological correlation and subsurface mapping
Determine facies and drilling locations
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Basic
Log
InterpretationBasic
Log
Interpretation Continued
Gamma Rays Self Potential
Resistivity
Induction
Density Neutron
Sonic
Magnetic Resonance
Formation Test
Common Tools in the Logging Industry
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Porosity
Water Saturation
Permeability
Fluid types
Fluid contacts
Lithology
Dip angle
Velocity
Basic Log InterpretationBasic Log Interpretation Continued
Typical properties implied or estimated from
the log Measurements:
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Porosity =Volume of pores
Total Volume of Rock
Porosity is estimated using one or combination of
the followings; - Density
- Neutron
- Sonic
Combination of three inputs will get better estimate
Porosity = Storage Capacity
POR = (DENmatrix DENlog)/(DENmatrix DENfluid)
Density Porosity:
Petrophysical PropertiesPetrophysical Properties
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SW =Formation Water in the pores
Total pore space in the rock
Water Saturation is estimated using combination of
the followings; - Porosity
- Resistivity
It requires formation factor and saturation index
derived from core analysis, and formation water resistivity
Petrophysical PropertiesPetrophysical Properties
Archies Equation
Sw =1/Por * Rw
Rt
SW - Water saturation
Rw - Formation water resistivity
Rt - True Formation resistivity
( )
1/n
n - Saturation exponent
m - Cementation factor
m
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Permeability Estimation from Logs
K=93 * Por
Swi
Permeability (K) is a measure of rock property to get the fluid passes through the rock.
The equations are based on empirical study, accurate K estimation can be obtained from
formation test, drillstem test (DST) or from core analysis
( )2.2 2
K=250 * Por
Swi( )
3 2
Timurs
Tixiers
where Swi = Irreducible water saturation
Petrophysical PropertiesPetrophysical Properties
bj ibj i
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ObjectivesObjectives
GettoknowvariouslogmeasurementsGettoknowvariouslogmeasurements
Recognizefluid
type
and
lithology
of
major
Recognize
fluid
type
and
lithology
of
major
reservoirs,andsomepracticalapplicationsoflogreservoirs,andsomepracticalapplicationsoflog
datadata
Familiarizewith
factors
affecting
the
log
responseFamiliarize
with
factors
affecting
the
log
response
UnderstandthestrategyinwellevaluationUnderstandthestrategyinwellevaluation
GettoknowvariousapproachestowellloggingdesignGettoknowvariousapproachestowellloggingdesign
Exercisewith
well
log
designExercise
with
well
log
design
Fluid and Lithology Identification From the LogsFluid and Lithology Identification From the Logs
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FluidandLithologyIdentificationFromtheLogsFluidandLithologyIdentificationFromtheLogs
Fluid and Lithology Identification From the LogsFluid and Lithology Identification From the Logs
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FluidandLithologyIdentificationFromtheLogsFluidandLithologyIdentificationFromtheLogs
Gas
Oil
Water
Oil-Water Contact
Gas-Oil Contact
Water filled Sand
Water filled Sand
Water filled Sand
Oil Sand
Gas Sand
Coal
Carbonate/Limestone
Fluid and Lithology Identif ication From the LogsFluid and Lithology Identif ication From the Logs
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RES0.1 100
Fluid and Lithology Identif ication From the LogsFluid and Lithology Identif ication From the Logs
Oil-Water Contact
Gas-Oil Contact
Water filled Sand
Water filled Sand
Water filled Sand
Oil Sand
Gas Sand
Coal
Carbonate/Limestone
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How
Can
We
Remember
These
Easily?How
Can
We
Remember
These
Easily?AboutLithologyInterpretation
Claystone haslargeamountofwater,andradioactivematerials,isdenserwhenithas
lesswater,isnotharderthanlimestoneandisveryconductive.
Sandstone islessdensethanlimestone,haslesswaterthanclay,containmorewater
thanlimestoneexceptwhenitissaturatedwithdrygas,itsconductivityisdependingon
fluidtypeitcontains,hassmalltononeradioactivefragments.
Limestone isharderthanbothclayandsand,containsleastwaterofthethree,very
resistive,ithaslowradioactivitymaterials,fastvelocity,highdensity.
Coal Normalylowradioactive,rarelyradioactive,lowestdensityandveryresistive
How Can We Remember These Easily?How Can We Remember These Easily?
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HowCanWeRememberTheseEasily?HowCanWeRememberTheseEasily?About
Fluid
Interpretation
HighRadioactivity HighGR
VeryConductive LowResistivity
HighWater
High
Neutron
and
Low
Resistivity
HighGas LowNeutronandHighResistivity
HighOil HigherNeutronthanGas,denser
thangasLessNeutronthanwater,
lessdensethanwater,more
resistivethan
water,
less
resistivethangaswhenother
propertiesarethesame
DryGas Veryresistive,largestdensity
neutroncrossover
High
GOR
Larger
density
neutron
crossover
thanoilwithlowGOR
FreshWater Reservoirfilledwithhighresistivewater
Are There Any Anomalies?Are There Any Anomalies?
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AreThereAnyAnomalies?AreThereAnyAnomalies?About
Fluid
Interpretation
InagaszoneMudfiltrateinvasionwillcausetheneutrondensity
crossoverlooks
like
that
of
oil
zone,
the
shallow
investigation
resistivitywillbelessresistivethanthatofdeeperdepthofinvestigation,resistivitydifferenceislargerwhenconductivemudisused
HighIrreduciblewater(waterboundsinclaysandgrains
surface)will
demonstrate
little
density
neutron
crossover
similartothatofoilorwaterzonesbutlessresistivethangasoroilzoneswithlessirreduciblewater
Inanoilzone similartoabove
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How Is Log Analysis Calibrated?How Is Log Analysis Calibrated?
Core Data
Routie Core Analysis - For Porosity and Permeability Calibration
Special Core Analysis - For detailed rock and fluid properties such as
X Ray Diffraction, Scanning Electron Microscopy, Petrophysical
parameters (a,m and n determination), PVT, Gas Analysis and finger
prints of fluid samples, and etc.
Formation Test
Fluid Identification from the logs is not direct, when the parameters are
not well established, formation test fluid samples can be used to
calibrate fluid identification using the logs. Formation test is also usedwhen possible log response anomalies encountered to get conclusive
fluid identification.
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Modern Formation For Fluid IdentificationModern Formation For Fluid Identification
Single Probe Module
Hydraulic Power ModuleHydraulic Power Module
Electric Power Module
Fluid Description ModuleFluid Description Module
MDT String Configuration
Multi sample ChambersMulti sample Chambers
Test ProbeTest Probe
Large sample ChamberLarge sample Chamber
Basic components of the toolBasic components of the tool
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BasiccomponentsofthetoolBasiccomponentsofthetool
Probe
Multi-sample
Chambers
Resist.
sensorPump Out
Module
Pre-Test
Strain Gauge
Quartz Gauge
Isolation
Valve
Optical Fluid
Analyzer
Flow line
Probe
HP GaugeValve
Pre-Test
Two Sample Chambers
OLDOLD NEWNEW
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OFA Gas Detector Optics
Gas Detector SystemGas Detector System
Light Emitting Diode
Cylindrical Lens
Polarizer
Fluid Flow GasLiquid
Gas
Sapphire
Prism
Photodetector
Array
Sapphire window
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OFA Spectrometer
How OFA Divice OperatesHow OFA Divice Operates
Fluid flowSapphire
Lamp
Light
Distributor
Source
Light path
Solenoids
MeasureLight Path
Filter lensPhotodiode
Chopper motor
Filter LensCatridge
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ExampleExample--1 : Gas OFA1 : Gas OFA
ExampleExample--2 : Water OFA2 : Water OFA
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Are There Any Other Logs Applications?Are There Any Other Logs Applications?
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AreThereAnyOtherLogsApplications?AreThereAnyOtherLogsApplications?
VolumeofHydrocarbon
Fluidcontinuity
ReservoirExtent
ReservoirRockProperties
DepositionalEnvirontment
Diagenesisand
Compaction
Trapping
Heterogeneity
Selecting Drilling Location
Well Completion
Subsurface Geological Mapping
Reservoir Characterization
All are useful for
The Logs Can Help Us to Determine:
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Hydrocarbon Reserves EstimateHydrocarbon Reserves Estimate
Oil rec = 7758 * (1-Sw) * h * Por * RF * ABoI
(43560 * DEPTH*0.43)* (1-Sw)* h* Por*RF*A
15
Where : RF - Recovery Factor
h - Thickness, A - Area
BoI - Oil Vol. factorBoI = 1.05 + 0.5 * (Gas Oil Ratio/100)
Gas rec =
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LateralContinuity
?Lateral
Continuity
?
Well-1 Well-2Well-7
GR Res
GR Res
GR Res
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CompactionTrend
?Compaction
Trend
?
GRRes
DT
ObjectivesObjectives
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GettoknowvariouslogmeasurementsGettoknowvariouslogmeasurements
Recognizefluid
type
and
lithology
of
major
reservoirs,
and
Recognize
fluid
type
and
lithology
of
major
reservoirs,
and
somepracticalapplicationsoflogdatasomepracticalapplicationsoflogdata
FamiliarizewithfactorsaffectingthelogresponseFamiliarizewithfactorsaffectingthelogresponse
UnderstandthestrategyinwellevaluationUnderstandthestrategyinwellevaluation
GettoknowvariousapproachestowellloggingdesignGettoknowvariousapproachestowellloggingdesign
ExercisewithwelllogdesignExercisewithwelllogdesign
Depth of Investigation and ResolutionDepth of Investigation and Resolution
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of Logging Toolsof Logging Tools
0 cm50 cm100 cm150 cm200 cm250 cm
2 cm
5 cm
60 cm
20 cm
30 cm
40 cm
80 cm
80 cm
Dipmeter
Micro resistivity
Micro log
Sonic
Density
Gamma-ray
Neutron
Laterolog
Induction
log
Resistivity
Radioactivity
Acoustic
Resistivity
Depth of Investigation
Reso
lution
Tools Size and Measuring point for TypicalTools Size and Measuring point for Typical
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AIT SDT LDT CNT SGT LEH TCC AMS
Additional combinable tools:
- Dipmeter
- Magnetic Resonance
- Borehole Imager
- Dipole Sonic
- Formation Tester
- Others
Oil Based Mud EnvironmentOil Based Mud Environment
Induction S
onic
Density
Neutron
GR
Measuring point from
the bottom of the tool
Tool Length
This slide helps you to configure the tool string that is appropriate for your well
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ResistivityMeasurementProblemsandLimitationsResistivityMeasurementProblemsandLimitations
Resistivity measurements are not reliable when you have:
Severe invasion due to overbalanced mudLarge washed-out borehole
Shoulder bed affects
High content of conductive minerals
Some older tool generations have limited vertical resolution
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Ri
Effectsof
Borehole
EnvironmentEffects
of
Borehole
Environment
Rm
Rxo
Rmf
Sxo
Ri
Rz
Si
Ro
Rt
RwSw
Undisturbed
Formation
InvadedZone
Flushed
Zone
Mud CakeRmc
i
fili
fil
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Invasion ProfileInvasion Profile
Fresh Mud Rmf > RW
Salt Mud Rmf < Rw
Rxo
Rxo
Rt
Rt
Rm
Rm
DMS
D M S
Low High
SPLogLimitationsSPLogLimitations
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The tool is only for water based borehole environment
SP is not reliable when you have no or very small contrast
between Formation water salinity and mud filtrate salinity resulting in no
to small SP deflection
GR Log LimitationsGR Log Limitations
Standard GR tool is not reliable when you log an interval with radioactive
mineral rich rocks. NGT is recommended to use for this type of
Formation to get reliable GR derived clay volume calculation.GR measurements in cased hole environment need to be normalized
due to casing, and cement attenuation
Density Log LimitationsDensity Log Limitations
Density log is a pad device, it is very sensitive to the pad contact with
The borehole wall, make sure to consult with your petrophysicist prior to
using the data for any other applications.
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Wh
Wi li
W ll
l iWh
Wi li
W ll
l i
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WhyWireline Well loggingWhy Wireline Well logging
1. Better Resolution
2. More advanced tools
3. Better depth control
4. Only choice available (certain tools)
5. More certain on data quality
DisadvantagesofWirelineDisadvantagesofWireline
l il i
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logginglogging
1. Invasion effect
2. Hole condition dependant
3. Unable to log in high angle wells (>60 deg)
4. Acquired after drilling, more rig time5. More uncertainty in getting data or good
data in problem prone wells
ImportantIssueswithImportantIssueswith
Running Wireline logsRunning Wireline logs
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RunningWireline
logsRunning
Wireline
logs
1. Borehole fluid type
2. Borehole size3. Well deviation
4. Tool combination5. High Mud Weight resulting in over balanced
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Logging while Drilling
WhyLWD?WhyLWD?
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ReduceRigTime
Real
Time
Decisions MinimizedBoreholeProblems
HighAngle/HorizontalWells
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LWDandWirelineComparisonLWDandWirelineComparison
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X800
X900
InvasionX800
X900
WirelineLogExampleWirelineLogExample
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X400
X450
LWDRealtimeandRecordedLogsLWDRealtimeandRecordedLogs
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GRGR
D. RES
D. RESDEN
DENNEUNEUX500
X600
X700
X500
X600
X700
SelectingtheToolstorunSelectingtheToolstorun
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Itdepends
on
what
type
of
information
you
are
about
to
get
andthecostyouarewillingtospend.
Need
Want
What is the value of information you are getting?
What tools do you run in the hole?
Ability
to
Define
Your
NeedAbility
to
Define
Your
Need
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Ability to Define Your NeedAbility to Define Your Need
Geological
Geophysical
Reservoir
Petrophysical
Mechanical
TypeofInformationtoAcquireTypeofInformationtoAcquire
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GeologyGeology
Sanddevelopmentandsandthickness
Stratigraphic
information
Lateralcontinuity
Hydrocarbonsource
GeophysicsGeophysics
Velocityuncertainty
Well
to
seismic
tie
Seismicandfluids/lithologycorrelation
TypeofInformationTypeofInformation continued
PetrophysicsPetrophysics
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PetrophysicsPetrophysicsPorosityWatersaturation
Permeability
Mineralogy
ReservoirReservoirCompartment
FluidpropertiesReservoirpressureReservoirmonitoring
RockMechanicsRockMechanics
StressdirectionPressureprofileFractureorientation
Understand
the
Scales
Of
ObservationUnderstand
the
Scales
Of
Observation
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Understand the Scales OfObservationUnderstand the Scales OfObservation
Seismic Section
Wireline Logs
Out-Crops/Core
Thin Sections
ScalesOfObservationScalesOfObservation
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Well Logging Design ObjectiveWell Logging Design Objective
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WellLogging
Design
ObjectiveWell
Logging
Design
Objective
The objectives of a well logging design should followyour drilling objectives, if drilling objective is not met,
the objectives of logging program should be adjusted
accordingly.
A logging program would vary depending on drilling
Objectives.
WellLoggingDesignWellLoggingDesign11
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OnshorewellOnshorewell
Adevelopmentwell,A5,istodrillupdipstructureofASandtoaccelerateoil production,theA4wellhasproducedthis
Reservoirforayear,andcurrentlyproduces80%water. The
reservoirhas
astrong
aquiver
drive
mechanism.
WellLoggingDesignWellLoggingDesign11 continued
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DrillingobjectiveistodrillandcompletetheASandLevel
Logging
program
objective
for
this
well
is
then
to
locate
the
topoftheASandandmakesurethattheintervalisstillintheoilcolumn.
Otherinformation:Strongwaterdrivemeansithasgood
pressure
maintenance,
therefore,
no
need
to
take
pressure
data.
Rigtype:OnshoreRig(inexpensive),averticalwell.
LoggingDesign:WirelineGRResistivityNeutronDensity
WellLoggingDesignWellLoggingDesign22
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OffshorewellOffshorewell
Athirdappraisalwellisproposedonthewestflankofthestructure. Firsttwowellssuggestthatwelltowelllog
correlationisnoteasy, howeverpressuredatahashelpedthe
well
to
well
correlation.
This
well
is
to
reveal
the
lateral
continuityandthecompartmentissueofthereservoirs.
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ExampleExample2 LoggingProgram2 LoggingProgram Continued
8 1/2 Hole Section 9000 to 12000 MD
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81/2HoleSection9000to12000MDLWD:GRResistivityDensityNeutron
Wireline:TriplecomboasacontingencywhenLWDfail
WetCase:TriplecomboasacontingencywhenLWDdataisnotreliable
Formation
tests
for
pressures
and
water
samplesH.C.Case:TriplecomboasacontingencywhenLWDdataisnotreliableFormationtestsforpressuresandfluidsamplesBoreholeimagelogfordipandstratigraphicinformationNuclearMagnetictoolwhenconsiderablethickshalysandreservoirsarepenetratedBoreholeseismicforvelocitysurvey
ImportantAspectsToConsiderImportantAspectsToConsider
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Risk
Cost
Environment
HoleSize
WellDesign
ToolSpeed
ImportantAspectsToConsiderImportantAspectsToConsider
Some
examplesSome
examples
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Risk
While
we
are
running
in
hole
with
wireline
tools,
the
toolscouldnotgodownatcertaindepth. Thecompany
representativehasdecidedtopulloutofholetorun
differenttoolconfiguration.
Incaseofariskthatwearenotabletogodownpassing
thesamedepthwithnewtoolconfiguration,the
petrophysicist
has
asked
the
log
engineer
to
log
up
while
pullingoutofholetogetdataassurance.
ImportantAspectsToConsiderImportantAspectsToConsider
Some
examplesSome
examples
C
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Cost
AfterthewellreachedTDat6000ft,theteamfoundout
thattheydonothaveroomtogetalllogdatatothebaseof
thereservoirnearTDiftheyusetypicaltriplecombination
wirelinetools,todrilladditional50ftwouldtake24hourrig
timeincluding
RIH
and
POOH.
Thepetrophysicisthasthendecidedtosplitthetoolsinto
tworuns,whichonlyrequireadditional6hourrigtimefor
secondwireline
run.
By
doing
that
it
would
have
saved
18
hourrigtimeiftheydrilladditional50fttohaveonlyone
loggingrun
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ImportantAspectsToConsiderImportantAspectsToConsider
Some
examplesSome
examples
H l Si
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HoleSize
TheDrillingengineerhassuggestedtorunonlyLWDinthe
121/4holesectiontoreducewellcost.
Thepetrophysicisthasarguedandsuggestedtorun
wirelinebecause
based
on
previous
wells
in
this
field
where
theyhavedrilledataveragerateof300ft/hrresultinginnot
reliabledata.Theteamhassupportedtheirpetrophysicistto
runwirelinebecauseitwouldhelptosupportfield
certification.
ImportantAspectsToConsiderImportantAspectsToConsiderSomeexamplesSomeexamples
Well Design
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WellDesign
AftertheG&Gteamprovidethetargetstothedrilling
engineer,theteamhastoendupwithawelldesignthatit
requiresahighlydeviatedwellexceeding60deg.
LWD
log
data
acquisition
is
then
put
in
their
logging
programbecausebasedontheirexperienceinthisfield50
degwellwasthehighestdeviatedwellthattheycouldlog
withwireline.
ImportantAspectsToConsiderImportantAspectsToConsiderSomeexamplesSomeexamples
Tool Speed
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ToolSpeed
BasedonthestatisticsdrillingthePliocenesectionisvery
quick,averaging400ft/hr,thecompanyisdrillingahorizontalgaswellatabout3000ftTVD.
LWD
engineer
and
the
petrophyscist
have
worked
together
andhavegivenarecommendationtodocontrolleddrillingat
about200ft/hrtogetanacceptablelogdataquality.
Whatdoyouhaveinmind?Whatdoyouhaveinmind?
On Shore Off Shore
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On Shore
Development Well
Off Shore
Deep water
development-well
In respect to Risk, Cost, Environment, Hole Size, Well Design, Tool Speed
ExploratoryWellExploratoryWell
Seismic Information
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SeismicInformation
RegionalGeologyInformation
DrillingthewellusingLearningwhiledoing
concept
HighRiskbutmustbemanageable
MostlyVerticalwell
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AnExampleofrathercomplexLoggingProgramAnExampleofrathercomplexLoggingProgram
DecisionTreeDecisionTree
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West Seno Data Gathering Strategy
Standard
well PAY
Fully
Loaded
Wireline
Full
Cores
SAMPLING
12 1/4
PAY
LWD
SAMPLES
LWD
WIRELINE
PRESSURE
P. O
PEX
MD T
CST
Cores
Special
Logging
Velocity
Uncertainty
UBI or CBL
SAMPLING
Cased Hole GR
CSAT
or VSP
GR to bottom of 13 3/8
STOPSTOP
Objective
driven-logging
Y
N
Y
Y YY
Y
Y
Y
Y
Y
YN
N
N
N
N
N
NN
N
N
N
N
LW D
MD T
Objective
Deepest
WellVSP
STOPN
Another
Way
To
Save
Cost!Another
Way
To
Save
Cost!
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ACQUIREDATAWITHOUTUSINGCOSTLYRIGTIME
(PIPEDECISION
NOT
NECESSARY
NO
DRY
HOLES)
GATHERDATAREALTIMEWHILEDRILLING
GATHERDATA
THROUGH
TUBING
AFTER
COMPLETION
COMBINATIONOFBOTH
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ProjectBaseApproachProjectBaseApproach
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UOMEcompanyhas$200MMprogramfor
exploratorywells
for
the
year
2004.
Asafollowupoftheirexplorationcampaign,
UOMECompany
has
$600
MM
program
for
developinganewdeepwaterfieldfortheyear
2005thatwillhavepeakproductionof100,000
BOPD
ObjectivesObjectives
Get to know various log measurementsGet to know various log measurements
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GettoknowvariouslogmeasurementsGettoknowvariouslogmeasurements
Recognizefluidtypeandthelithologyofmajorreservoirs,Recognizefluidtypeandthelithologyofmajorreservoirs,
andpractical
uses
of
log
dataand
practical
uses
of
log
data
FamiliarizewithfactorsaffectingthelogresponseFamiliarizewithfactorsaffectingthelogresponse
UnderstandthestrategyinwellevaluationUnderstandthestrategyinwellevaluation
Getto
know
various
well
logging
designsGet
to
know
various
well
logging
designs
ExercisewithwelllogdesignExercisewithwelllogdesign
Exercise1
PTIndooilCo.,thesoleownerofmineralrightonBlockA,onshore,2kminadjacenttoaknownoilproducingareaintheBlockB. Thecompanyislookingata
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j p g p y gprospecttodrillthefirstwell,Indoco1,intheblocktargetingforthesameproducingintervalinBlockBatabout4000ftdepth,anditisestimated50ftdown
dip
in
this
block. Thecostsforvariousavailablelogdataacquisitionareasfollow:
WirelineGR$1/ft,Induction$4/ft,BHCSonic$1/ft,Density$2/ft,Neutron$2/ft
Formationtest$100/pressure,$1000/fluididentification,$2000/fluidsample
DepthchargeforeachWirelinetoolisfree.
LWD
GR
and
Induction
$10,000/day,
Density
and
Neutron
$10,000/day Therigcostis$5000/day
1)Whatisyourrecommendeddatagatheringstrategyandwellloggingdesignforthewell?
2)Whiledrilling,thewellpenetrates5thicksandunitswithhighmudloggasfrom3,000to4,200ft. Howdoyourecommendthecompanyontheloggingdesign?
3)After
the
well
reached
the
proposed
TD,
there
were
no
encouragement
seen
from
themudlogsigns,whatwouldyoudoforyourloggingprogram?
Exercise2
Theexercise1wasseismicallytotesttheamplitudeanomalyat Orange horizon equivalent to the Berani Clastic Formation
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atOrangehorizon,equivalenttotheBeraniClasticFormation.TheIndoco1wellencountered300ftofOilcolumnandwas
completedand
produced
from
this
level
for
over
one
year
withcumulativeproductionof4mmbo. Thecompanyislookingatsimilarseismiccharacter11/2kmawayfromIndoco1well,whichwasconnectedbydimeventtotheamplitudeattheIndoco1well. Ithasbeeninterpretedasa
differentchannel
lobe.
The
company
did
low
profile
and
ran
onlysimplewirelineGR,resistivity,density,neutronandsonicontheInoco1well.
WhatisyourdatagatheringstrategyforthisIndoco2well?
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Exercise4
AnoffshorewellisproposedtoredrilltheA5welli h di di i f hi ll h l
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withupdipdirectionfromthiswelltogetthegasleg
of
clean
and
blocky
sand
found
with
gas
water
contactintheA5well. Thecompanyistryingtogetmoregasproduction. Theteamislookingatdrillinghorizontalwellwithabout500ftofproducing
section.
Whatis
your
recommended
logging
programforthiswellandwhy?